CN201418040Y - A driving circuit for a synchronous rectifier - Google Patents

A driving circuit for a synchronous rectifier Download PDF

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CN201418040Y
CN201418040Y CN2009201356200U CN200920135620U CN201418040Y CN 201418040 Y CN201418040 Y CN 201418040Y CN 2009201356200 U CN2009201356200 U CN 2009201356200U CN 200920135620 U CN200920135620 U CN 200920135620U CN 201418040 Y CN201418040 Y CN 201418040Y
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synchronous rectifier
signal
circuit
shutdown
voltage
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魏德功
官继红
曾建斌
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    • Y02B70/00Technologies for an efficient end-user side electric power management and consumption
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Abstract

本实用新型提供了一种同步整流管的驱动电路,其包括:关断预处理电路,用于从同步整流管的漏极获取检测信号,并将该信号与第一标准电压相比,产生于预关断信号;与所述关断预处理电路输出端相连的过零比较放大电路,用于采集所述同步整流管的源极信号,并将该信号与第二标准电压相比,当所述源极信号大于所述标准电压与漏源间电压之和时,输出所述同步整流管的导通驱动电信号使所述同步整流管处于饱和状态;当所述源极信号小于所述标准电压与漏源间电压之和时,且通过控制端接收到所述预关断信号时,输出所述同步整流管预关断的预关断驱动电信号使所述同步整流管处于非饱和状态。本实用新型能够提供预关断处理过程,从而缩短了同步整流管的关断时间。

Figure 200920135620

The utility model provides a drive circuit for a synchronous rectifier, which includes: a shut-off preprocessing circuit for obtaining a detection signal from the drain of the synchronous rectifier, and comparing the signal with a first standard voltage to generate Pre-shutdown signal; a zero-crossing comparison amplifier circuit connected to the output terminal of the shutdown preprocessing circuit, used to collect the source signal of the synchronous rectifier tube, and compare the signal with the second standard voltage, when the When the source signal is greater than the sum of the standard voltage and the drain-source voltage, output the conduction drive electrical signal of the synchronous rectifier to make the synchronous rectifier in a saturated state; when the source signal is less than the standard When the sum of the voltage and the drain-source voltage is received, and when the pre-shutdown signal is received through the control terminal, a pre-shutdown drive signal for the synchronous rectifier to be pre-shutdown is output to make the synchronous rectifier in an unsaturated state . The utility model can provide a pre-shutdown process, thereby shortening the shutoff time of the synchronous rectifier tube.

Figure 200920135620

Description

A kind of drive circuit of synchronous rectifier
Technical field
The utility model relates to a kind of control circuit of power supply, specifically, relates to a kind of drive circuit of synchronous rectifier.
Background technology
At present, the main synchronous rectification that has been extensive use of replaces traditional diode rectifier in the power supply of the big stream output of low pressure, to improve power-efficient, energy savings.What but traditional synchronous rectification had will use the process auxiliary drive winding, and what have will make current transformer, the use that has integrated circuit, integrated numerous element, the cost height, control is complicated, and in using limitation is arranged, can't realize synchronous rectification all topological structures.
The utility model content
The utility model provides a kind of drive circuit of synchronous rectifier, and it can provide pre-shutoff processing procedure, thereby has shortened the turn-off time of synchronous rectifier.
To achieve these goals, the utility model adopts following technical scheme:
The utility model provides a kind of drive circuit of synchronous rectifier, and it comprises: turn-off pre-process circuit, be used for obtaining detection signal from the drain electrode of synchronous rectifier, and this signal is compared with first normal voltage, result from pre-cut-off signals; The zero balancing amplifying circuit excessively that links to each other with described shutoff pre-process circuit output, be used to gather the source signal of described synchronous rectifier, and this signal compared with second normal voltage, during the voltage sum, the conducting of exporting described synchronous rectifier drives the signal of telecommunication makes described synchronous rectifier be in saturation condition between described source signal is greater than described normal voltage and drain-source; Between described source signal is less than described normal voltage and drain-source during the voltage sum, and when receiving described pre-cut-off signals, exports the pre-pre-shutoff of turn-offing of described synchronous rectifier and drive the signal of telecommunication and makes described synchronous rectifier be in unsaturated state by control end.
The utility model effect: the utility model adopts exclusive shutoff preliminary treatment circuit, the turn-off time of prediction synchronous rectifier, before turn-offing, synchronous rectifier earlier the control voltage of synchronous rectifier is reduced to a reduced levels, prepare for turn-offing synchronous rectifier, when the current over-zero of synchronous rectifier, can rapidly synchronous rectifier be turn-offed, shortened the turn-off time greatly, reverse current is little.Exclusive zero-crossing switching circuit just turn-offs synchronous rectifier when the synchronous rectification tube current reaches zero point, and the shutoff sequential is accurate, does not have diode current flow problem in the synchronous rectification body, need not extra Schottky in parallel.The utility model is applied widely, is not only applicable to the synchronous rectification of continuous current mode, also can be used for the synchronous rectification of the critical and electric current non-continuous mode of electric current.
Description of drawings
Fig. 1 is the utility model electrical block diagram;
Fig. 2 is the utility model one embodiment electrical block diagram;
Fig. 3 is the another embodiment electrical block diagram of the utility model;
Fig. 4 is a circuit each several part operating voltage oscillogram of the present utility model.
Embodiment
Describe specific implementation of the present utility model in detail below with reference to accompanying drawing.
As shown in Figure 1, the drive circuit of a kind of synchronous rectifier that the utility model provides, it mainly comprises following two parts:
1, turn-offs pre-process circuit 300, be used for obtaining detection signal, and this signal is compared with the first normal voltage V1, result from pre-cut-off signals from the drain electrode of synchronous rectifier T1;
2, cross zero balancing amplifying circuit 100, it links to each other with the output that turn-offs pre-process circuit 300, be used to gather the source signal of described synchronous rectifier T1, and this signal compared with the second normal voltage V2, during the voltage sum, the conducting of output synchronous rectifier T1 drives the signal of telecommunication makes synchronous rectifier T1 be in saturation condition between described source signal is greater than described normal voltage V2 and drain-source; Between described source signal is less than described normal voltage V2 and drain-source during the voltage sum, and when receiving described pre-cut-off signals by control end, the pre-pre-shutoff of turn-offing of output synchronous rectifier T1 drives the signal of telecommunication makes described synchronous rectifier T1 be in unsaturated state, comprises off state or magnifying state.
Compared with prior art, the utility model was by realizing collection to the source signal of synchronous rectifier T1 from increasing zero balancing amplifying circuit 100, and acquisition corresponding driving signal, in order to guarantee that circuit can be stably turn-offs rapidly when the current over-zero, then also increase by one and turn-offed pre-process circuit 300, be used to produce pre-cut-off signals, the controlling and driving signal makes synchronous rectifier T1 be in unsaturated state, comprises off state or magnifying state.
As shown in Figure 1, the shutoff pre-process circuit 300 here comprises: comparator A2, integrating capacitor C2, and integrating resistor R1, the end of integrating resistor R1 is used to connect the drain electrode of synchronous rectifier T1, the other end of integrating resistor R1 connects the end of integrating capacitor C2 and the input of comparator A2, another termination signal ground of integrating capacitor C2, another input of comparator A2 connects signal ground by the second normal voltage V2, and the output of comparator A2 is used to export described pre-cut-off signals.
For the stability of circuit, in described shutoff pre-process circuit 300, also comprise: be connected on the drain electrode of synchronous rectifier T1 and the capacitance C1 between the integrating resistor R1.
In order to limit the size of current of described pre-cut-off signals, in described shutoff pre-process circuit 300, also comprise: the output and the described current-limiting resistance R2 that crosses between the zero balancing amplifying circuit 100 that are connected on described comparator A2.
In view of shutoff pre-process circuit 100 structures shown in Figure 1, for integrating capacitor C2 is resetted, described drive circuit also comprises: the integrating capacitor reset circuit 400 that links to each other with described shutoff pre-process circuit 300 outputs, be used for when the described pre-cut-off signals of described shutoff pre-process circuit 300 outputs, described integrating capacitor C2 being resetted.Shown in Figure 1, integrating capacitor reset circuit 400 comprises: inverter ic 1, with door IC2 and switch element IC3, the output of described comparator A2 connects an input described and door IC2 by inverter ic 1, the output of described comparator A2 connects another input described and door IC2, described output with door IC2 is connected the control end of described switch element IC3, described switch element IC3 is connected in parallel on the two ends of described integrating capacitor, when described comparator A2 exported described pre-cut-off signals, described switch element IC3 closure made described integrating capacitor C2 discharge reduction.Here the switch element IC3 that is carried can be triode T31, a diode D31 in parallel between its collector and emitter, as shown in Figures 2 and 3.
As shown in Figure 1, the above-mentioned zero balancing amplifying circuit 100 of crossing comprises: controlled relatively amplifying unit A1, and the first normal voltage V1, the control end of described controlled amplifying unit A1 connects the output of described shutoff pre-process circuit 300, the described controlled relatively input of amplifying unit A1 is used for connecting by the first normal voltage V1 drain electrode of described synchronous rectifier T1, and described controlled relatively another input of amplifying unit A1 is used to connect the source electrode of described synchronous rectifier T1.In addition, if controlled amplifying unit A1 adopts operational amplifier, then increase impedance Z and realize negative feedback.
As shown in Figure 1, the first normal voltage V1 can adopt DC power supply, but Fig. 3 gives the realization circuit of the another kind of first normal voltage V1, it comprises: resistance R 12, diode D12, diode D13, triode T12, resistance R 11, DC power supply VCC, the negative electrode of diode D12 connects the base stage of triode T12, the emitter of triode T12 connects the source electrode of described synchronous rectifier T1 by resistance R 11, the anode of diode D12 and diode D13 is connected the output of DC power supply VCC by resistance R 12, and the negative electrode of diode D13 connects the described controlled relatively input of amplifying unit A1.In addition, as shown in Figure 1, controlled relatively amplifying unit A1 adopts controlled high speed operation amplifier, and as shown in Figures 2 and 3, controlled relatively amplifying unit A1 comprises triode T11, capacitor C 11, and capacitor C 11 is connected in parallel between the collector and emitter of triode T11, and the base stage of triode T11 links to each other with the negative electrode of diode D13, the emitter of triode T11 connects the source electrode of described synchronous rectifier T1, and the collector electrode of triode T11 connects the output of described shutoff pre-process circuit 300.In order to overcome the error that element device parameter matching causes, in Fig. 3, increased element D12 and D13, element D12 and element D13, elements T 12 is consistent with the T13 parameter, thereby complementary, has overcome the conforming problem that component parameters error and variations in temperature cause.
In order to increase driving force, described drive circuit also comprises: be connected on the power amplification circuit 200 between the described grid of crossing zero balancing amplifying circuit 100 outputs and synchronous rectifier T1.Its complementary output level that can adopt triode to constitute realizes 200 parts as shown in Figures 2 and 3.As shown in Figure 2, power amplifying part is made of compound transistor T21, T22 and triode T23, and its input links to each other with the collector electrode of triode T11, and output is connected with the control grid of synchronous rectifier T1, it is an electric current driving amplifier, and output voltage equates with input voltage.
With Fig. 2 and two given specific embodiments of Fig. 3, operation principle of the present utility model is described below.
As shown in Figure 1, illustrate that with the continuous current mode circuit of reversed excitation its basic principle is as follows:
1. turn-off the preliminary treatment circuit in advance: establish circuit and reached stable state, institute's charging voltage is last negative just down on the capacitance C1, and its voltage equals electric power output voltage, and it is zero that the voltage on the integrating capacitor C2 has been put.It is disconnected that the transformer secondary output coil is in the beginning rank that reset, at this moment, because of the appearance value of capacitance C1 appearance value much larger than integrating capacitor C2, can think that the voltage of capacitor C 1 is constant substantially, the resetting voltage of coil 1 charges to integrating capacitor C2 by resistance, after reseting procedure was finished, the electric capacity of capacitor C 2 was charged to certain value.At this moment, coil voltage overturns, coil begins discharge through synchronous rectifier to capacitor C 3, simultaneously, integrating capacitor is also discharged to coil L by integrating resistor R1, since inductance to discharge and recharge weber value equal, also equate and be worth the ampere-second of capacitor charge and discharge, obviously, when coil discharge finishes when entering next switch periods, voltage on the integrating capacitor C2 is also put and is 0V, has inserted a reference voltage V 2 on comparator A2, by the comparison of voltage on the integrating capacitor C2 and reference voltage V 2, thereby drawn pre-cut-off signals, this signal is reflected in the output of comparator A2 and is: when the voltage on the integrating capacitor C2 is lower than the voltage of reference voltage source V2, be output as low level, electric current flows into common ports from controlled output voltage amplifier through resistance R 2, then controlled operational amplifier A 1 is output as a low voltage, synchronous rectifier T1 breaks away from the saturation region and enters the amplification region, prepares for next step shutoff, has finished pre-shutoff.
2. current over-zero compares amplifying circuit: the negative terminal at the controlled output voltage high speed operation amplifier of element A1 connects the drain electrode that is connected to synchronous rectifier T1 through a reference voltage source V1, the source electrode that just is connected to synchronous rectifier T1 of element A1.
(1) opens the stage, when transformer time limit winding L begins to discharge, its polarity is last negative just down, diode current flow in the synchronous rectification body, its drain voltage hangs down about 0.7V approximately than source voltage, because the voltage of reference voltage source V1 is far below 0.7V, at this moment, operational amplifier A 1 is output as high level, and output also is high level after power discharge device 200 amplifies, and homogeneous tube T1 is open-minded synchronously.
(2) open the maintenance stage, after synchronous rectifier T1 opens, because the voltage Vsd on the synchronous rectifier still is higher than the voltage of joining voltage source V 1, operational amplifier A 1 is output as high level, and this process lasts till that always comparator A2 provides till the pre-cut-off signals.
(3) pre-turn off process, when transformer secondary output coil L discharge process closes to an end, comparator A2 output low level, the Control current of operational amplifier A 1 flows back to common port through resistance R 2, operational amplifier A 1 controlled signal, output voltage is reduced to about 4V, after power amplifier 200 amplified, synchronous rectifier T1 voltage reduced, and broke away from saturation condition, enter magnifying state, because the threshold values shutoff voltage of synchronous rectifier T1 is about 3V, that is to say that the control pole tension of synchronous rectifier T1 only need reduce 1V more just can enter off state, obviously, reducing to 3V with respect to traditional control pole tension from about the 10V just turn-offs then and can shorten the turn-off time greatly.
(4) the dynamic conducting resistance adjustment of synchronous rectifier rank are disconnected, when power source loads is light, because the discharging current of secondary coil L is less, synchronous rectifier T1 after opening soon its tube voltage drop Vsd just less than the voltage of reference voltage source V1, the output voltage of operational amplifier A 1 reduces, force the Vgs voltage of synchronous rectifier T1 to descend, the on state resistance of synchronous rectifier T1 increases, make its Vsd voltage rise, because the negative feedback of impedance network Z, make the output voltage of operational amplifier A 1 finally reach stable state at the voltage Vsd of synchronous rectifier T1 when equaling the voltage of reference voltage source V1, this process is a lasting adjustment process.When power source loads is heavier, this adjustment process is then very of short duration, because this moment, the discharging current of secondary coil L was bigger, voltage drop Vsd on the synchronous rectifier T1 is always greater than the voltage of reference voltage source V1, open up to the primary switch pipe, secondary coil L electric current descends rapidly, and as the pressure drop Vsd of synchronous rectifier T1 during less than the voltage of reference voltage source V1, adjustment process begins.
(5) synchronous rectifier current over-zero turn off process, when secondary coil L discharge stream constantly is reduced to zero, the dynamic conducting resistance of synchronous rectifier T1 is adjusted the disconnected end in rank, output capacitance C3 begins to discharge to secondary coil L through synchronous rectifier T1, because counter-rotating has taken place in electric current, under the effect of impedance network Z, the course of work of comparator A2 is a strong positive feedback process, promptly the voltage drop Vds owing to synchronous rectifier T1 constantly raises, the output voltage of operational amplifier A 1 then constantly reduces, corresponding with it synchronous rectifier T1 control pole tension Vgs also constantly reduces, the conducting resistance of synchronous rectifier T1 also constantly increases, the then corresponding rising of its pressure drop Vds, so process is a positive feedback process, synchronous rectifier T1 turn-offs rapidly.Secondary coil L enters reseting procedure, enters next switch periods.Need to prove at this, when the electric current of synchronous rectifier T1 arrives zero, corresponding with it synchronous rectifier T1 control pole tension should corresponding effect through operational amplifier A 1 adjust to zero, promptly reach shutoff, because in the process of big electric current continuous operation, di/dt is bigger, electric current is very of short duration to zero this process from big electric current, and the regular hour is wanted in the shutoff of synchronous rectifier T1, so just turn-off this process after zero passage is arranged, and because pre-effect of turn-offing the preliminary treatment circuit, it is also very of short duration to turn-off this process after the synchronous rectifier T1 zero passage, reverse current is less, and only for using the reverse recovery current level of Schottky as rectification circuit, detailed process can be referring to oscillogram shown in Figure 4 in actual measurement.From the whole process of circuit, there is not synchronous rectifier to close this process of diode current flow in the synchronous rectifier body of having no progeny, shown in Fig. 4 (b), therefore do not need to solve the recovery problem that diode current flow brought in the synchronous rectification body for synchronous rectifier Schottky in parallel.
3. integrating capacitor reset circuit: when dynamic load is worked, can accurately provide pre-cut-off signals in order to ensure this circuit, therefore will guarantee to start from scratch, discharge into zero and finish in each switch periods integrating capacitor charging voltage.When secondary coil L discharge process will finish, voltage on the integrating capacitor C2 progressively reduces and approaches zero, and less than reference voltage V 2, comparator A2 is output as low level, behind reverser IC1, be output as high level send into the door IC2 an input, at the voltage identical with synchronous rectifier Vgs with the voltage that another input inserted of door IC2, because secondary discharge also end this moment, the Vgs of synchronous rectifier is a high level signal, so IC2 exports a high level signal at this moment with door, the electronic switch IC3 that resets opens after the secondary coil discharge process finishes, synchronous rectifier T1 turn-offs, its Vgs voltage is zero, be low level promptly with door IC2 one input terminal voltage, with the output voltage of door IC2 be low level also, the electronic switch IC3 that resets turn-offs, finished the resetting of integrating capacitor C2, integrating capacitor enters next switch periods integral process.
As shown in Figure 2, relatively amplifying circuit 100 can also be by resistance R 11 for the synchronous rectifier current over-zero, resistance R 12, resistance R 13, capacitor C 11, diode D11 and triode T11 constitute, wherein resistance R 12 provides a reference current, this electric current R11 that flows through produces a reference voltage, the junction voltage of diode D11 equates with the BE junction voltage of triode T11, when big electric current is flowed through synchronous rectifier, its Vsd is far above the voltage of R11, the reference current that provides through resistance R 11 is all through diode D11, resistance R 12 flows into the drain electrode of synchronous rectifier, no current flows through in the BE knot of triode T11, triode ends, so the Vgs of synchronous rectifier T1 obtains a high voltage, synchronous rectifier T1 conducting.When the current over-zero of the synchronous rectifier T1 that flows through, its pressure drop Vsd also is 0V, so 1/2 BE that flows through triode T11 of the reference current that R12 produced ties triode T11 saturation conduction, thereby the Vgs voltage of synchronous rectifier T1 is pulled to end level, and synchronous rectifier T1 ends.When the electric current that flows through synchronous rectifier T1 hour, the voltage drop that produces on synchronous rectifier T1 is less, be Vsd less than the pressure drop of resistance R 11 but greater than zero, then the reference current of resistance R 12 generations has small part to flow through the BE knot of triode T11, triode T11 is in magnifying state, thereby the Vgs voltage of adjusting synchronous rectifier T1 reduces, the corresponding increase of its conducting resistance, make Vsd increase, maintain the voltage levvl of resistance R 11, this process is a lasting adjustment process, and capacitor C 11 is used to eliminate the vibration that is in course of adjustment and produces.The pre-preliminary treatment circuit that turn-offs is made of capacitance C1, integrating resistor R1, integrating capacitor C2, reference voltage V 2, OC door output comparator A2 and resistance R 2.When comparator A2 obtained pre-cut-off signals and is output as a low level, resistance R 13 constituted the dividing potential drops relation with resistance R 2, thereby had dragged down the output voltage of power amplifier.
Illustrating of above-mentioned each concrete steps is comparatively concrete; can not therefore think restriction to scope of patent protection of the present utility model; above-mentioned pre-shutoff preliminary treatment circuit, integrating capacitor reset circuit, current over-zero comparison amplifying circuit, power amplification drive circuit all can adopt above-mentioned each circuit; perhaps its variant, scope of patent protection of the present utility model should be as the criterion with claims.

Claims (10)

1、一种同步整流管的驱动电路,其特征在于,包括:1. A drive circuit for a synchronous rectifier, characterized in that it comprises: 关断预处理电路,用于从同步整流管的漏极获取检测信号,并将该信号与第一标准电压相比,产生于预关断信号;Turn off the pre-processing circuit, which is used to obtain the detection signal from the drain of the synchronous rectifier, and compare the signal with the first standard voltage to generate the pre-shutdown signal; 与所述关断预处理电路输出端相连的过零比较放大电路,用于采集所述同步整流管的源极信号,并将该信号与第二标准电压相比,输出所述同步整流管的导通驱动电信号使所述同步整流管处于饱和状态;或者,输出所述同步整流管预关断的预关断驱动电信号使所述同步整流管处于非饱和状态。The zero-crossing comparison amplifier circuit connected to the output terminal of the shutdown preprocessing circuit is used to collect the source signal of the synchronous rectifier, compare the signal with the second standard voltage, and output the synchronous rectifier Turning on the driving electrical signal makes the synchronous rectifier in a saturated state; or outputting a pre-off driving electrical signal for pre-shutting off the synchronous rectifier to make the synchronous rectifier in a non-saturated state. 2、根据权利要求1所述的驱动电路,其特征在于,所述驱动电路还包括:串联在所述过零比较放大电路输出端与同步整流管的栅极之间的功率放大电路。2. The drive circuit according to claim 1, further comprising: a power amplifier circuit connected in series between the output terminal of the zero-crossing comparison amplifier circuit and the gate of the synchronous rectifier. 3、根据权利要求1所述的驱动电路,其特征在于,所述关断预处理电路包括:比较器、积分电容、及积分电阻,所述积分电阻的一端用于连接所述同步整流管的漏极,所述积分电阻的另一端连接所述积分电容的一端和所述比较器的一输入端,所述积分电容的另一端接信号地,所述比较器的另一输入端通过所述第二标准电压接信号地,所述比较器的输出端用于输出所述预关断信号。3. The driving circuit according to claim 1, wherein the shutdown preprocessing circuit comprises: a comparator, an integrating capacitor, and an integrating resistor, one end of the integrating resistor is used to connect to the synchronous rectifier Drain, the other end of the integrating resistor is connected to one end of the integrating capacitor and an input end of the comparator, the other end of the integrating capacitor is connected to the signal ground, and the other input end of the comparator is connected through the The second standard voltage is connected to the signal ground, and the output terminal of the comparator is used to output the pre-shutdown signal. 4、根据权利要求3所述的驱动电路,其特征在于,所述关断预处理电路还包括:串联在所述同步整流管的漏极与所述积分电阻之间的隔直电容。4. The driving circuit according to claim 3, wherein the shutdown preprocessing circuit further comprises: a DC blocking capacitor connected in series between the drain of the synchronous rectifier and the integrating resistor. 5、根据权利要求3所述的驱动电路,其特征在于,所述关断预处理电路还包括:串联在所述比较器的输出端与所述过零比较放大电路之间的限流电阻。5. The driving circuit according to claim 3, wherein the shutdown preprocessing circuit further comprises: a current limiting resistor connected in series between the output terminal of the comparator and the zero-crossing comparison amplifier circuit. 6、根据权利要求3所述的驱动电路,其特征在于,所述驱动电路还包括:与所述关断预处理电路输出端相连的积分电容复位电路,用于当所述关断预处理电路输出所述预关断信号时,对所述积分电容进行复位。6. The drive circuit according to claim 3, characterized in that, the drive circuit further comprises: an integrating capacitor reset circuit connected to the output terminal of the shutdown pre-processing circuit, for when the shutdown pre-processing circuit When the pre-shutdown signal is output, the integration capacitor is reset. 7、根据权利要求6所述的驱动电路,其特征在于,所述积分电容复位电路包括:反相器、与门和开关单元,所述比较器的输出端通过反相器连接所述与门的一输入端,所述比较器的输出端连接所述与门的另一输入端,所述与门的输出端连接所述开关单元的控制端,所述开关单元并联在所述积分电容的两端,当所述比较器输出所述预关断信号时,所述开关单元闭合使所述积分电容放电复位。7. The driving circuit according to claim 6, wherein the integrating capacitor reset circuit comprises: an inverter, an AND gate and a switch unit, the output terminal of the comparator is connected to the AND gate through the inverter One input terminal of the comparator, the output terminal of the comparator is connected to the other input terminal of the AND gate, the output terminal of the AND gate is connected to the control terminal of the switching unit, and the switching unit is connected in parallel to the integrating capacitor When the comparator outputs the pre-shutdown signal, the switch unit is closed to reset the discharge of the integrating capacitor. 8、根据权利要求1所述的驱动电路,其特征在于,所述过零比较放大电路包括:可控比较放大单元、及第一标准电压,所述可控放大单元的控制端连接所述关断预处理电路的输出端,所述可控比较放大单元的一输入端用于通过第一标准电压连接所述同步整流管的漏极,所述可控比较放大单元的另一输入端用于连接所述同步整流管的源极。8. The drive circuit according to claim 1, wherein the zero-crossing comparison amplifier circuit comprises: a controllable comparison amplifier unit and a first standard voltage, the control terminal of the controllable amplifier unit is connected to the switch The output terminal of the off preprocessing circuit, one input terminal of the controllable comparison amplifier unit is used to connect the drain of the synchronous rectifier tube through the first standard voltage, and the other input terminal of the controllable comparison amplifier unit is used for Connect to the source of the synchronous rectifier. 9、根据权利要求8所述的驱动电路,其特征在于,提供所述第一标准电压的电路包括:电阻R12、二极管D12、二极管D13、三极管T12、电阻R11、直流电源VCC,二极管D12的阴极连接三极管T12的基极,三极管T12的发射极通过电阻R11连接所述同步整流管的源极,二极管D12和二极管D13的阳极通过电阻R12连接直流电源VCC的输出端,二极管D13的阴极连接所述可控比较放大单元的一输入端。9. The driving circuit according to claim 8, wherein the circuit providing the first standard voltage comprises: resistor R12, diode D12, diode D13, transistor T12, resistor R11, DC power supply VCC, and the cathode of diode D12 Connect the base of the triode T12, the emitter of the triode T12 is connected to the source of the synchronous rectifier through the resistor R11, the anodes of the diode D12 and the diode D13 are connected to the output end of the DC power supply VCC through the resistor R12, and the cathode of the diode D13 is connected to the An input terminal of the controllable comparison amplifier unit. 10、根据权利要求8或9所述的驱动电路,其特征在于,所述可控比较放大单元采用可控高速运算放大器。10. The driving circuit according to claim 8 or 9, wherein the controllable comparison and amplification unit adopts a controllable high-speed operational amplifier.
CN2009201356200U 2009-03-07 2009-03-07 A driving circuit for a synchronous rectifier Expired - Fee Related CN201418040Y (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102195492A (en) * 2011-05-24 2011-09-21 成都芯源系统有限公司 Synchronous rectification switching power supply and control circuit and control method thereof
CN102735914A (en) * 2012-05-10 2012-10-17 成都芯源系统有限公司 Synchronous rectification circuit and zero-crossing detection method
CN105305844A (en) * 2015-10-21 2016-02-03 无锡市芯茂微电子有限公司 Isolated type synchronous rectification control circuit, device and method
CN115224914A (en) * 2022-08-08 2022-10-21 绍兴光大芯业微电子有限公司 Synchronous rectification chip pre-turn-off circuit structure for realizing flyback topology

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102195492A (en) * 2011-05-24 2011-09-21 成都芯源系统有限公司 Synchronous rectification switching power supply and control circuit and control method thereof
CN102735914A (en) * 2012-05-10 2012-10-17 成都芯源系统有限公司 Synchronous rectification circuit and zero-crossing detection method
CN102735914B (en) * 2012-05-10 2014-12-31 成都芯源系统有限公司 synchronous rectification circuit and zero-crossing detection method
CN105305844A (en) * 2015-10-21 2016-02-03 无锡市芯茂微电子有限公司 Isolated type synchronous rectification control circuit, device and method
CN105305844B (en) * 2015-10-21 2017-11-21 深圳市芯茂微电子有限公司 A kind of isolated form synchronous commutating control circuit and its device and control method
CN115224914A (en) * 2022-08-08 2022-10-21 绍兴光大芯业微电子有限公司 Synchronous rectification chip pre-turn-off circuit structure for realizing flyback topology
CN115224914B (en) * 2022-08-08 2024-03-22 绍兴光大芯业微电子有限公司 Synchronous rectification chip pre-turn-off circuit structure for realizing flyback topology

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